Non-volatile memory is an electronic memory device. Because of having some features such as being capable of maintaining information without additional power, fast data access and shockproof capacity, non-volatile memory is widely used in memory cards, solid state drives and portable multimedia devices. When data stored in a non-volatile memory is read many times, the non-volatile memory may have read disturbance which may lead to improper data storage. Therefore, the non-volatile memory must be refreshed; however, the refresh may affect the service life of the non-volatile memory.